/*
 * GiST support for ltree
 * Teodor Sigaev <teodor@stack.net>
 * contrib/ltree/ltree_gist.c
 */
#include "postgres.h"

#include "access/gist.h"
#include "access/stratnum.h"
#include "crc32.h"
#include "ltree.h"

#define NEXTVAL(x) ( (lquery*)( (char*)(x) + INTALIGN( VARSIZE(x) ) ) )

PG_FUNCTION_INFO_V1(ltree_gist_in);
PG_FUNCTION_INFO_V1(ltree_gist_out);

Datum
ltree_gist_in(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("ltree_gist_in() not implemented")));
    PG_RETURN_DATUM(0);
}

Datum
ltree_gist_out(PG_FUNCTION_ARGS)
{
    ereport(ERROR,
            (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
             errmsg("ltree_gist_out() not implemented")));
    PG_RETURN_DATUM(0);
}

PG_FUNCTION_INFO_V1(ltree_compress);
PG_FUNCTION_INFO_V1(ltree_decompress);
PG_FUNCTION_INFO_V1(ltree_same);
PG_FUNCTION_INFO_V1(ltree_union);
PG_FUNCTION_INFO_V1(ltree_penalty);
PG_FUNCTION_INFO_V1(ltree_picksplit);
PG_FUNCTION_INFO_V1(ltree_consistent);

#define ISEQ(a,b)    ( (a)->numlevel == (b)->numlevel && ltree_compare(a,b)==0 )
#define GETENTRY(vec,pos) ((ltree_gist *) DatumGetPointer((vec)->vector[(pos)].key))

Datum
ltree_compress(PG_FUNCTION_ARGS)
{
    GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
    GISTENTRY  *retval = entry;

    if (entry->leafkey)
    {                            /* ltree */
        ltree_gist *key;
        ltree       *val = (ltree *) DatumGetPointer(PG_DETOAST_DATUM(entry->key));
        int32        len = LTG_HDRSIZE + VARSIZE(val);

        key = (ltree_gist *) palloc0(len);
        SET_VARSIZE(key, len);
        key->flag = LTG_ONENODE;
        memcpy((void *) LTG_NODE(key), (void *) val, VARSIZE(val));

        retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
        gistentryinit(*retval, PointerGetDatum(key),
                      entry->rel, entry->page,
                      entry->offset, FALSE);
    }
    PG_RETURN_POINTER(retval);
}

Datum
ltree_decompress(PG_FUNCTION_ARGS)
{
    GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
    ltree_gist *key = (ltree_gist *) DatumGetPointer(PG_DETOAST_DATUM(entry->key));

    if (PointerGetDatum(key) != entry->key)
    {
        GISTENTRY  *retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));

        gistentryinit(*retval, PointerGetDatum(key),
                      entry->rel, entry->page,
                      entry->offset, FALSE);
        PG_RETURN_POINTER(retval);
    }
    PG_RETURN_POINTER(entry);
}

Datum
ltree_same(PG_FUNCTION_ARGS)
{
    ltree_gist *a = (ltree_gist *) PG_GETARG_POINTER(0);
    ltree_gist *b = (ltree_gist *) PG_GETARG_POINTER(1);
    bool       *result = (bool *) PG_GETARG_POINTER(2);

    *result = false;
    if (LTG_ISONENODE(a) != LTG_ISONENODE(b))
        PG_RETURN_POINTER(result);

    if (LTG_ISONENODE(a))
        *result = (ISEQ(LTG_NODE(a), LTG_NODE(b))) ? true : false;
    else
    {
        int32        i;
        BITVECP        sa = LTG_SIGN(a),
                    sb = LTG_SIGN(b);

        if (LTG_ISALLTRUE(a) != LTG_ISALLTRUE(b))
            PG_RETURN_POINTER(result);

        if (!ISEQ(LTG_LNODE(a), LTG_LNODE(b)))
            PG_RETURN_POINTER(result);
        if (!ISEQ(LTG_RNODE(a), LTG_RNODE(b)))
            PG_RETURN_POINTER(result);

        *result = true;
        if (!LTG_ISALLTRUE(a))
        {
            LOOPBYTE
            {
                if (sa[i] != sb[i])
                {
                    *result = false;
                    break;
                }
            }
        }
    }

    PG_RETURN_POINTER(result);
}

static void
hashing(BITVECP sign, ltree *t)
{
    int            tlen = t->numlevel;
    ltree_level *cur = LTREE_FIRST(t);
    int            hash;

    while (tlen > 0)
    {
        hash = ltree_crc32_sz(cur->name, cur->len);
        HASH(sign, hash);
        cur = LEVEL_NEXT(cur);
        tlen--;
    }
}

Datum
ltree_union(PG_FUNCTION_ARGS)
{
    GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
    int           *size = (int *) PG_GETARG_POINTER(1);
    BITVEC        base;
    int32        i,
                j;
    ltree_gist *result,
               *cur;
    ltree       *left = NULL,
               *right = NULL,
               *curtree;
    bool        isalltrue = false;
    bool        isleqr;

    MemSet((void *) base, 0, sizeof(BITVEC));
    for (j = 0; j < entryvec->n; j++)
    {
        cur = GETENTRY(entryvec, j);
        if (LTG_ISONENODE(cur))
        {
            curtree = LTG_NODE(cur);
            hashing(base, curtree);
            if (!left || ltree_compare(left, curtree) > 0)
                left = curtree;
            if (!right || ltree_compare(right, curtree) < 0)
                right = curtree;
        }
        else
        {
            if (isalltrue || LTG_ISALLTRUE(cur))
                isalltrue = true;
            else
            {
                BITVECP        sc = LTG_SIGN(cur);

                LOOPBYTE
                    ((unsigned char *) base)[i] |= sc[i];
            }

            curtree = LTG_LNODE(cur);
            if (!left || ltree_compare(left, curtree) > 0)
                left = curtree;
            curtree = LTG_RNODE(cur);
            if (!right || ltree_compare(right, curtree) < 0)
                right = curtree;
        }
    }

    if (isalltrue == false)
    {
        isalltrue = true;
        LOOPBYTE
        {
            if (((unsigned char *) base)[i] != 0xff)
            {
                isalltrue = false;
                break;
            }
        }
    }

    isleqr = (left == right || ISEQ(left, right)) ? true : false;
    *size = LTG_HDRSIZE + ((isalltrue) ? 0 : SIGLEN) + VARSIZE(left) + ((isleqr) ? 0 : VARSIZE(right));

    result = (ltree_gist *) palloc0(*size);
    SET_VARSIZE(result, *size);
    result->flag = 0;

    if (isalltrue)
        result->flag |= LTG_ALLTRUE;
    else
        memcpy((void *) LTG_SIGN(result), base, SIGLEN);

    memcpy((void *) LTG_LNODE(result), (void *) left, VARSIZE(left));
    if (isleqr)
        result->flag |= LTG_NORIGHT;
    else
        memcpy((void *) LTG_RNODE(result), (void *) right, VARSIZE(right));

    PG_RETURN_POINTER(result);
}

Datum
ltree_penalty(PG_FUNCTION_ARGS)
{
    ltree_gist *origval = (ltree_gist *) DatumGetPointer(((GISTENTRY *) PG_GETARG_POINTER(0))->key);
    ltree_gist *newval = (ltree_gist *) DatumGetPointer(((GISTENTRY *) PG_GETARG_POINTER(1))->key);
    float       *penalty = (float *) PG_GETARG_POINTER(2);
    int32        cmpr,
                cmpl;

    cmpl = ltree_compare(LTG_GETLNODE(origval), LTG_GETLNODE(newval));
    cmpr = ltree_compare(LTG_GETRNODE(newval), LTG_GETRNODE(origval));

    *penalty = Max(cmpl, 0) + Max(cmpr, 0);

    PG_RETURN_POINTER(penalty);
}

/* used for sorting */
typedef struct rix
{
    int            index;
    ltree       *r;
} RIX;

static int
treekey_cmp(const void *a, const void *b)
{
    return ltree_compare(
                         ((const RIX *) a)->r,
                         ((const RIX *) b)->r
        );
}


Datum
ltree_picksplit(PG_FUNCTION_ARGS)
{
    GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
    GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1);
    OffsetNumber j;
    int32        i;
    RIX           *array;
    OffsetNumber maxoff;
    int            nbytes;
    int            size;
    ltree       *lu_l,
               *lu_r,
               *ru_l,
               *ru_r;
    ltree_gist *lu,
               *ru;
    BITVEC        ls,
                rs;
    bool        lisat = false,
                risat = false,
                isleqr;

    memset((void *) ls, 0, sizeof(BITVEC));
    memset((void *) rs, 0, sizeof(BITVEC));
    maxoff = entryvec->n - 1;
    nbytes = (maxoff + 2) * sizeof(OffsetNumber);
    v->spl_left = (OffsetNumber *) palloc(nbytes);
    v->spl_right = (OffsetNumber *) palloc(nbytes);
    v->spl_nleft = 0;
    v->spl_nright = 0;
    array = (RIX *) palloc(sizeof(RIX) * (maxoff + 1));

    /* copy the data into RIXes, and sort the RIXes */
    for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j))
    {
        array[j].index = j;
        lu = GETENTRY(entryvec, j); /* use as tmp val */
        array[j].r = LTG_GETLNODE(lu);
    }

    qsort((void *) &array[FirstOffsetNumber], maxoff - FirstOffsetNumber + 1,
          sizeof(RIX), treekey_cmp);

    lu_l = lu_r = ru_l = ru_r = NULL;
    for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j))
    {
        lu = GETENTRY(entryvec, array[j].index);    /* use as tmp val */
        if (j <= (maxoff - FirstOffsetNumber + 1) / 2)
        {
            v->spl_left[v->spl_nleft] = array[j].index;
            v->spl_nleft++;
            if (lu_r == NULL || ltree_compare(LTG_GETRNODE(lu), lu_r) > 0)
                lu_r = LTG_GETRNODE(lu);
            if (LTG_ISONENODE(lu))
                hashing(ls, LTG_NODE(lu));
            else
            {
                if (lisat || LTG_ISALLTRUE(lu))
                    lisat = true;
                else
                {
                    BITVECP        sc = LTG_SIGN(lu);

                    LOOPBYTE
                        ((unsigned char *) ls)[i] |= sc[i];
                }
            }
        }
        else
        {
            v->spl_right[v->spl_nright] = array[j].index;
            v->spl_nright++;
            if (ru_r == NULL || ltree_compare(LTG_GETRNODE(lu), ru_r) > 0)
                ru_r = LTG_GETRNODE(lu);
            if (LTG_ISONENODE(lu))
                hashing(rs, LTG_NODE(lu));
            else
            {
                if (risat || LTG_ISALLTRUE(lu))
                    risat = true;
                else
                {
                    BITVECP        sc = LTG_SIGN(lu);

                    LOOPBYTE
                        ((unsigned char *) rs)[i] |= sc[i];
                }
            }
        }
    }

    if (lisat == false)
    {
        lisat = true;
        LOOPBYTE
        {
            if (((unsigned char *) ls)[i] != 0xff)
            {
                lisat = false;
                break;
            }
        }
    }

    if (risat == false)
    {
        risat = true;
        LOOPBYTE
        {
            if (((unsigned char *) rs)[i] != 0xff)
            {
                risat = false;
                break;
            }
        }
    }

    lu_l = LTG_GETLNODE(GETENTRY(entryvec, array[FirstOffsetNumber].index));
    isleqr = (lu_l == lu_r || ISEQ(lu_l, lu_r)) ? true : false;
    size = LTG_HDRSIZE + ((lisat) ? 0 : SIGLEN) + VARSIZE(lu_l) + ((isleqr) ? 0 : VARSIZE(lu_r));
    lu = (ltree_gist *) palloc0(size);
    SET_VARSIZE(lu, size);
    lu->flag = 0;
    if (lisat)
        lu->flag |= LTG_ALLTRUE;
    else
        memcpy((void *) LTG_SIGN(lu), ls, SIGLEN);
    memcpy((void *) LTG_LNODE(lu), (void *) lu_l, VARSIZE(lu_l));
    if (isleqr)
        lu->flag |= LTG_NORIGHT;
    else
        memcpy((void *) LTG_RNODE(lu), (void *) lu_r, VARSIZE(lu_r));


    ru_l = LTG_GETLNODE(GETENTRY(entryvec, array[1 + ((maxoff - FirstOffsetNumber + 1) / 2)].index));
    isleqr = (ru_l == ru_r || ISEQ(ru_l, ru_r)) ? true : false;
    size = LTG_HDRSIZE + ((risat) ? 0 : SIGLEN) + VARSIZE(ru_l) + ((isleqr) ? 0 : VARSIZE(ru_r));
    ru = (ltree_gist *) palloc0(size);
    SET_VARSIZE(ru, size);
    ru->flag = 0;
    if (risat)
        ru->flag |= LTG_ALLTRUE;
    else
        memcpy((void *) LTG_SIGN(ru), rs, SIGLEN);
    memcpy((void *) LTG_LNODE(ru), (void *) ru_l, VARSIZE(ru_l));
    if (isleqr)
        ru->flag |= LTG_NORIGHT;
    else
        memcpy((void *) LTG_RNODE(ru), (void *) ru_r, VARSIZE(ru_r));

    v->spl_ldatum = PointerGetDatum(lu);
    v->spl_rdatum = PointerGetDatum(ru);

    PG_RETURN_POINTER(v);
}

static bool
gist_isparent(ltree_gist *key, ltree *query)
{
    int32        numlevel = query->numlevel;
    int            i;

    for (i = query->numlevel; i >= 0; i--)
    {
        query->numlevel = i;
        if (ltree_compare(query, LTG_GETLNODE(key)) >= 0 && ltree_compare(query, LTG_GETRNODE(key)) <= 0)
        {
            query->numlevel = numlevel;
            return true;
        }
    }

    query->numlevel = numlevel;
    return false;
}

static ltree *
copy_ltree(ltree *src)
{
    ltree       *dst = (ltree *) palloc0(VARSIZE(src));

    memcpy(dst, src, VARSIZE(src));
    return dst;
}

static bool
gist_ischild(ltree_gist *key, ltree *query)
{
    ltree       *left = copy_ltree(LTG_GETLNODE(key));
    ltree       *right = copy_ltree(LTG_GETRNODE(key));
    bool        res = true;

    if (left->numlevel > query->numlevel)
        left->numlevel = query->numlevel;

    if (ltree_compare(query, left) < 0)
        res = false;

    if (right->numlevel > query->numlevel)
        right->numlevel = query->numlevel;

    if (res && ltree_compare(query, right) > 0)
        res = false;

    pfree(left);
    pfree(right);

    return res;
}

static bool
gist_qe(ltree_gist *key, lquery *query)
{
    lquery_level *curq = LQUERY_FIRST(query);
    BITVECP        sign = LTG_SIGN(key);
    int            qlen = query->numlevel;

    if (LTG_ISALLTRUE(key))
        return true;

    while (qlen > 0)
    {
        if (curq->numvar && LQL_CANLOOKSIGN(curq))
        {
            bool        isexist = false;
            int            vlen = curq->numvar;
            lquery_variant *curv = LQL_FIRST(curq);

            while (vlen > 0)
            {
                if (GETBIT(sign, HASHVAL(curv->val)))
                {
                    isexist = true;
                    break;
                }
                curv = LVAR_NEXT(curv);
                vlen--;
            }
            if (!isexist)
                return false;
        }

        curq = LQL_NEXT(curq);
        qlen--;
    }

    return true;
}

static int
gist_tqcmp(ltree *t, lquery *q)
{
    ltree_level *al = LTREE_FIRST(t);
    lquery_level *ql = LQUERY_FIRST(q);
    lquery_variant *bl;
    int            an = t->numlevel;
    int            bn = q->firstgood;
    int            res = 0;

    while (an > 0 && bn > 0)
    {
        bl = LQL_FIRST(ql);
        if ((res = memcmp(al->name, bl->name, Min(al->len, bl->len))) == 0)
        {
            if (al->len != bl->len)
                return al->len - bl->len;
        }
        else
            return res;
        an--;
        bn--;
        al = LEVEL_NEXT(al);
        ql = LQL_NEXT(ql);
    }

    return Min(t->numlevel, q->firstgood) - q->firstgood;
}

static bool
gist_between(ltree_gist *key, lquery *query)
{
    if (query->firstgood == 0)
        return true;

    if (gist_tqcmp(LTG_GETLNODE(key), query) > 0)
        return false;

    if (gist_tqcmp(LTG_GETRNODE(key), query) < 0)
        return false;

    return true;
}

static bool
checkcondition_bit(void *checkval, ITEM *val)
{
    return (FLG_CANLOOKSIGN(val->flag)) ? GETBIT(checkval, HASHVAL(val->val)) : true;
}

static bool
gist_qtxt(ltree_gist *key, ltxtquery *query)
{
    if (LTG_ISALLTRUE(key))
        return true;

    return ltree_execute(
                         GETQUERY(query),
                         (void *) LTG_SIGN(key), false,
                         checkcondition_bit
        );
}

static bool
arrq_cons(ltree_gist *key, ArrayType *_query)
{
    lquery       *query = (lquery *) ARR_DATA_PTR(_query);
    int            num = ArrayGetNItems(ARR_NDIM(_query), ARR_DIMS(_query));

    if (ARR_NDIM(_query) > 1)
        ereport(ERROR,
                (errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
                 errmsg("array must be one-dimensional")));
    if (array_contains_nulls(_query))
        ereport(ERROR,
                (errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
                 errmsg("array must not contain nulls")));

    while (num > 0)
    {
        if (gist_qe(key, query) && gist_between(key, query))
            return true;
        num--;
        query = NEXTVAL(query);
    }
    return false;
}

Datum
ltree_consistent(PG_FUNCTION_ARGS)
{
    GISTENTRY  *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
    StrategyNumber strategy = (StrategyNumber) PG_GETARG_UINT16(2);

    /* Oid        subtype = PG_GETARG_OID(3); */
    bool       *recheck = (bool *) PG_GETARG_POINTER(4);
    ltree_gist *key = (ltree_gist *) DatumGetPointer(entry->key);
    void       *query = NULL;
    bool        res = false;

    /* All cases served by this function are exact */
    *recheck = false;

    switch (strategy)
    {
        case BTLessStrategyNumber:
            query = PG_GETARG_LTREE(1);
            res = (GIST_LEAF(entry)) ?
                (ltree_compare((ltree *) query, LTG_NODE(key)) > 0)
                :
                (ltree_compare((ltree *) query, LTG_GETLNODE(key)) >= 0);
            break;
        case BTLessEqualStrategyNumber:
            query = PG_GETARG_LTREE(1);
            res = (ltree_compare((ltree *) query, LTG_GETLNODE(key)) >= 0);
            break;
        case BTEqualStrategyNumber:
            query = PG_GETARG_LTREE(1);
            if (GIST_LEAF(entry))
                res = (ltree_compare((ltree *) query, LTG_NODE(key)) == 0);
            else
                res = (
                       ltree_compare((ltree *) query, LTG_GETLNODE(key)) >= 0
                       &&
                       ltree_compare((ltree *) query, LTG_GETRNODE(key)) <= 0
                    );
            break;
        case BTGreaterEqualStrategyNumber:
            query = PG_GETARG_LTREE(1);
            res = (ltree_compare((ltree *) query, LTG_GETRNODE(key)) <= 0);
            break;
        case BTGreaterStrategyNumber:
            query = PG_GETARG_LTREE(1);
            res = (GIST_LEAF(entry)) ?
                (ltree_compare((ltree *) query, LTG_GETRNODE(key)) < 0)
                :
                (ltree_compare((ltree *) query, LTG_GETRNODE(key)) <= 0);
            break;
        case 10:
            query = PG_GETARG_LTREE_COPY(1);
            res = (GIST_LEAF(entry)) ?
                inner_isparent((ltree *) query, LTG_NODE(key))
                :
                gist_isparent(key, (ltree *) query);
            break;
        case 11:
            query = PG_GETARG_LTREE(1);
            res = (GIST_LEAF(entry)) ?
                inner_isparent(LTG_NODE(key), (ltree *) query)
                :
                gist_ischild(key, (ltree *) query);
            break;
        case 12:
        case 13:
            query = PG_GETARG_LQUERY(1);
            if (GIST_LEAF(entry))
                res = DatumGetBool(DirectFunctionCall2(ltq_regex,
                                                       PointerGetDatum(LTG_NODE(key)),
                                                       PointerGetDatum((lquery *) query)
                                                       ));
            else
                res = (gist_qe(key, (lquery *) query) && gist_between(key, (lquery *) query));
            break;
        case 14:
        case 15:
            query = PG_GETARG_LQUERY(1);
            if (GIST_LEAF(entry))
                res = DatumGetBool(DirectFunctionCall2(ltxtq_exec,
                                                       PointerGetDatum(LTG_NODE(key)),
                                                       PointerGetDatum((lquery *) query)
                                                       ));
            else
                res = gist_qtxt(key, (ltxtquery *) query);
            break;
        case 16:
        case 17:
            query = DatumGetPointer(PG_DETOAST_DATUM(PG_GETARG_DATUM(1)));
            if (GIST_LEAF(entry))
                res = DatumGetBool(DirectFunctionCall2(lt_q_regex,
                                                       PointerGetDatum(LTG_NODE(key)),
                                                       PointerGetDatum((ArrayType *) query)
                                                       ));
            else
                res = arrq_cons(key, (ArrayType *) query);
            break;
        default:
            /* internal error */
            elog(ERROR, "unrecognized StrategyNumber: %d", strategy);
    }

    PG_FREE_IF_COPY(query, 1);
    PG_RETURN_BOOL(res);
}
